1. Field of the Invention
The present invention relates to a rotary motor and a stator used for driving a medium used in a magnetic disk drive unit, optical disk drive unit or the like. More particularly, the present invention relates to the structure of the rotary motor and the stator in order to improve the mass productivity and to a method of manufacturing thereof.
2. Description of Related Art
A conventional rotary motor stator of this type (not shown) manufactured by stacking a plurality of ring-shaped board members blanking directly from a steel board, as disclosed in JP-A-100823/1982, for instance. However, yield of materials is low. For this reason, JP-B-46620/1985 discloses the improved yield by winding a belt-shaped board member with a large number of teeth in spiral while plastically deforming the board member to fasten a several layers by welding the respective layers.
As an another conventional method of manufacturing the rotary motor, there is a method disclosed in JP-A-98774/1999. FIGS. 48 and 49 are a view showing such a method.
Referring to FIGS. 48 and 49, the method involves feeding a strip-shaped magnetic material 500 to a press machine 502 through a work feeding machine 501, forming a core member 503 consists of thinned portions 503a, yoke members 503b, and magnetic pole teeth 503c, forming ring-shaped stacked yoke members 505 by winding a reel 504 by a plurality of turns such that the core member 503 corresponding to a plurality of stator cores are arranged during one turn, winding driving coils 506, dividing ring-shaped stacked yoke member 505 into blocks such that a stator core 507 corresponding to one rotary motor is provided, and producing stators for rotary motors by bending the stator core 507 with a tool.
The conventional rotary motor stators are constructed as above. Thus, the stator disclosed in JP-A-100823/1982 has not only the low yield of materials as mentioned above, but also is heavy to assemble thereof as the assembly forces a great number of the board members to be grasped one by one for conveyance. The stator disclosed in JP-B-46620/1985 has a difficulty in unfolding and dividing the stators for winding as the belt-shaped board member is wound up in spiral while plastically deforming. Regardless, they lack productivity.
Moreover, the method of manufacturing rotary motors disclosed in JP-A-98774/1999 has also the following problems.
(1) The diameter of connected stator cores 507 is very large compared with the thickness of stacked yoke member 505 for the reason that stator cores 507 corresponding to a plurality of rotary motors are connected in the circumferential direction. Therefore, the stacked yoke members 505 are apt to sag, which makes worse handling of stacked yoke members 505 in coating them with insulation coating and placing them onto the winding machine.
(2) It is difficult to provide a positioning portion for mounting the stator core 507 on the rotary motor and a stator-connecting for forming the stator core 507 in a ring and holding it for the reason that the yoke members having the same shape are continuously produced and they are wound up.
(3) The magnetic pole teeth 503c are stacked on the slant for the reason that the strip-shaped magnetic material 500 is provided with yoke members and the strip-shaped magnetic material 500 is wound up in a spiral form around a reel to form stacked yoke members 505. As a result, this incurs the deteriorated productivity in the winding process, and the decreased driving torque of the rotary motor and the torque ripple thereof.
The present invention has been made to solve the above problems. An object of the invention is to provide a stacked stator core capable of improving the workability in the winding process and the productivity of the product and a method of manufacturing the stator, and a rotary motor equipped with the stator and a method of manufacturing the rotary motor.
The stacked stator core to according to the present invention includes a first core member formed by stacking a prescribed number of magnetic materials and made up of a plurality of yoke members connected to one another through a bendable bent portion; a second core member formed by stacking the prescribed number of magnetic materials and made up of a yoke member arranged in such a manner that one end of each magnetic material of the second core member is successively connected to the other end of the first core member through a bendable bent portion from the next magnetic material of the other end of the first core member by shifting entirely the second core member downwards, with left the same number of stages of one end of the second core member unconnected as the prescribed number of stages; a third core member formed by stacking the prescribed number of magnetic materials, each of which is made up of the same number of yoke members as the first core member connected through the bendable bent portion, and one end of the magnetic material of the third core member is connected to the other end of the second core member through a bendable bent portion by shifting entirely the third core member downwards; and a fourth core member formed by stacking the prescribed number of magnetic materials and made up of a yoke member arranged in such a manner that one end of each magnetic material of the fourth core member is successively connected to the next stage of the other end of the third core member through a bendable bent portion from the next magnetic material of the other end of the third core member by shifting entirely the fourth core member downwards, with left the same number of stages of one end of the fourth core member unconnected as the prescribed number of sages; wherein the first, the second, the third and the fourth core members are independently arranged in a ring and mutually stacked.
This provides a stacked stator core able to easily unfold and divide winding.
The method of manufacturing a stator according to the present invention, includes the steps of forming the stacked stator core by blanking a magnetic material of claim 1 using a progressive die; unfolding the stacked stator core straight; subjecting the straight stacked stator core to a prescribed treatment; winding a wire around the straight stacked stator core subjected to the prescribed treatment; and winding up the straight wire-wound stacked stator core to restore the core to its original arrangement in a ring.
This provides a method of manufacturing a stator able to improve the workability in the winding process and the mass productivity.
The method of manufacturing a stacked stator core according to the present invention includes a plurality of stator cores, each of which is made up of a prescribed number of stacked sheet magnetic materials; a plurality of yoke members forming each stator core; a bendable bent portion provided between the yoke members; and an interconnecting portion for interconnecting the plurality of stator cores by connecting the upper end of one stator core to the lower end of the other stator core with a difference in level provided between the plurality of stator cores.
This provides a stator core able to easily unfold and divide wiring.
The method of manufacturing a rotary core according to the present invention includes a stator connected both ends of the stator core by bending a stator core in a ring having a plurality of stator cores, each made up of a prescribed number of stacked sheet magnetic materials; a plurality of yoke members forming each the stator core; a bendable bent portion provided between the yoke members; and an interconnecting portion for interconnecting the plurality of stator cores by connecting the upper end of one stator core to the lower end of the other stator core with a difference in level provided between the plurality of stator cores; and a base member equipped with the stator core.
This provides a rotary motor superior in the mass productivity.
The disk drive unit according to the present invention includes a stator core divided from a stacked stator core provided with a plurality of stator cores, each stator core makde up of a prescribed number of stacked sheet magnetic materials; a plurality of yoke members forming each stator core; a bendable bent portion provided between the yoke members; an interconnecting portion for interconnecting the plurality of stator cores by connecting the top of one stator core to the bottom of the other stator core with a difference in level provided between the plurality of stator cores; and a portion for reading and writing data from and to magnetic recording media rotated by the rotary motor.
This provides a slim and low-cost disk drive unit.
The method of manufacturing a rotary motor according to the present invention includes the steps of stacking a prescribed number of ring-shaped sheet magnetic materials provided with a plurality of yoke members and having a first divided portion at one place between the yoke members and a bent portion at the other place therebetween, such that each first divided portion is placed at the same position; stacking a prescribed number of sheet magnetic materials such that second divided portions thereof are placed with a prescribed number shifted by a unit of yoke members in the circumferential direction relative to the prescribed number of stacked sheet magnetic materials; successively stacking the sheet magnetic materials to form a stacked stator core by repeating the two steps as many as a desired number of times; elongating the bent portions of the stacked stator core to unfold the stacked stator core straight; winding driving coils around the magnetic pole teeth provided on the yoke members; dividing the wound yoke members into stator blocks; and forming a ring-shaped stator by bending the divided stator at the bending portion and connecting both ends thereof.
This provides the workability in the winding process and the mass productivity of a stator and rotary motor.
The method of manufacturing a rotary motor according to the present invention includes stacking a prescribed number of ring-shaped sheet magnetic materials provided with a plurality of yoke members and having a bent portion between the yoke members and a first divided portion in the vicinity of one the bent portion, such that each first divided portion is placed at the same position; stacking a prescribed number of sheet magnetic materials having a second divided portion at the position opposed to the first divided portion through the bent portion on the stacked sheet magnetic materials, such that each second divided portion is placed at the same position; stacking a prescribed number of sheet magnetic materials such that third divided portions thereof are positioned with a prescribed number shifted by a unit of yoke members in the circumferential direction relative to the prescribed number of stacked sheet magnetic materials having the second divided portion; successively stacking the sheet magnetic materials to form a stacked stator core by repeating the three steps as many as a desired number of times. elongating the bent portions of the stacked stator core to unfold the stacked stator straight; winding driving coils around the magnetic pole teeth provided on the yoke members; dividing the wound yoke members into stator blocks; and forming a ring-shaped stator by bending the divided stator at the bending portion and connecting both ends thereof.
This improves the workability in the winding process and the mass productivity of a rotary motor.